Mr. Spitzer, a Democrat, said he was eager to plunge back into politics and believed he could revolutionize the often-overlooked city office into a new model for government accountability and shareholder activism.

"I'm hopeful there will be forgiveness, I am asking for it," he said in a telephone interview on Sunday night.

Spitzer, who had great success fighting corruption on Wall Street as attorney general of New York, told the Times he wanted to turn the office of comptroller into a "obust agency that would not merely monitor and account for city spending, as it does now, but conduct regular inquiries into the effectiveness of government policies, in areas like education."

In order to make it onto the September primary ballot, Spitzer needs to collect 3,750 signatures from registered Democrats by Thursday.